I went from contractor to "real employee" at a big company and it was no problem keeping the same take-home pay, while also getting paid vacation, cheaper insurance, 401k matching, etc., etc. I feel a little burned for not asking for more money, but nobody would actually take less money, right?
It's interesting seeing differences between countries. Like the author said in the comments, 401k isn't an "issue" in Australia. I don't know how 401k works, but Superannuation in Aus is a compulsory 9%-10% of your salary that your employer sends to your super fund (that you can't access until you're 60). If you're a contractor you don't have to pay yourself super (so you could have more immediately available money), but you could also put away 9% just like your employer would. There's no insurance issues because we get government provided healthcare, and depending on the contract structure you go with there's actually a few decent protections an employer is required to provide you (if you structure it that you're a company contracting to another company then you're out of luck there).
So realistically the major difference is "security", which to be honest there isn't much of regardless you being an employee or contractor. So at least in Australia, unless you're getting an increase in your hourly rate, or a company says they'll only continue to send you work if you're an employee, there's no major advantage to switching to be an employee.